We are investigating acoustic and physiologica factors in spastic dysphonia a voice disorder - in order to provide information about its etiology, typology and possibly to improve the current diagnostic and treatment methodology. Work completed thus suggests that: 1) based on acoustic-perceptual and temporal measures of voice and speech, the currently used diagnostic procedure comprising temporary unilateral chemical paralysis of a recurrent laryngeal nerve (RLN) is a powerful predictor of the changes in voice and speedch occurring postsurgically as a result of RLN section; 2) thirty percent of examined segments of the RLN from patients with spastic dysphonia show structural abnoramlities histologically when compared to age-matched control RLNs; 3) in some of the patients examined spstic dysphonia coexists with well-defined neurologic disorders. Although it is uncertain how these histologic and neurologic findings account for spastic dysphonia, our data tend to suggest an organic basis for this disorder.